A comprehensive optimization of the sensitivity of CdS/CdIn2S4 composites to triethylamine gas

The physical and chemical properties of CdIn 2 S 4 can be effectively regulated by changing the composition and phase structure to present a rich diversity, making it a potential new gas sensing material. However, CdIn 2 S 4 has the characteristics of low carrier mobility and difficult separation of electrons and holes, which greatly hinders its development in the fields of gas sensing and catalysis. In this work, a sulfur-vacancy-rich CdS/CdIn 2 S 4 heterojunction composite was constructed by a one-step hydrothermal method for gas sensing, and the built-in electric field was used to effectively promote the separation and transfer of charges. Moreover, the introduction of sulfur vacancies increases the content of chemisorbed oxygen, which provides more reactive sites for the target gas, thereby realizing the improvement of gas sensing performance. Compared with the CdIn 2 S 4 sensor, the CdS/CdIn 2 S 4 sensor exhibited higher response to triethylamine (10 ppm-32.5), faster response/recovery time (3 s/256 s) and achieved a lower limit of detection at the ppb level (500 ppb-5.2). This work provides a new solution for real-time monitoring of low-concentration triethylamine gas. • Porous CdS/CdIn 2 S 4 nanoflowers were successfully synthesized by a one-step hydrothermal method. • A variety of techniques were employed to analyze the chemical and structural properties of the samples. • The response of the composites to formaldehyde was nearly three times that of pure CdIn 2 S 4 . • The effects of built-in electric field and sulfur vacancies on the improvement of sensing performances were discussed.